From patchwork Thu Sep 12 13:50:05 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Dr. David Alan Gilbert" X-Patchwork-Id: 11143237 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 3FE3C14ED for ; Thu, 12 Sep 2019 14:30:13 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 1F2FE2081B for ; Thu, 12 Sep 2019 14:30:13 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1F2FE2081B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Received: from localhost ([::1]:35198 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i8Q6u-0001io-0v for patchwork-qemu-devel@patchwork.kernel.org; Thu, 12 Sep 2019 10:30:12 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:40657) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i8PUy-0007Ky-HI for qemu-devel@nongnu.org; Thu, 12 Sep 2019 09:51:01 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1i8PUx-0003Hq-CG for qemu-devel@nongnu.org; Thu, 12 Sep 2019 09:51:00 -0400 Received: from mx1.redhat.com ([209.132.183.28]:60981) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1i8PUx-0003HN-4f for qemu-devel@nongnu.org; Thu, 12 Sep 2019 09:50:59 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 72DAC190C006; Thu, 12 Sep 2019 13:50:58 +0000 (UTC) Received: from dgilbert-t580.localhost (unknown [10.36.118.12]) by smtp.corp.redhat.com (Postfix) with ESMTP id 21E445D704; Thu, 12 Sep 2019 13:50:56 +0000 (UTC) From: "Dr. David Alan Gilbert (git)" To: qemu-devel@nongnu.org, ivanren@tencent.com, peterx@redhat.com, richardw.yang@linux.intel.com, yury-kotov@yandex-team.ru, quintela@redhat.com Date: Thu, 12 Sep 2019 14:50:05 +0100 Message-Id: <20190912135006.14820-12-dgilbert@redhat.com> In-Reply-To: <20190912135006.14820-1-dgilbert@redhat.com> References: <20190912135006.14820-1-dgilbert@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.6.2 (mx1.redhat.com [10.5.110.70]); Thu, 12 Sep 2019 13:50:58 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PULL 11/12] migration/qemu-file: fix potential buf waste for extra buf_index adjustment X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" From: Wei Yang In add_to_iovec(), qemu_fflush() will be called if iovec is full. If this happens, buf_index is reset. Currently, this is not checked and buf_index would always been adjust with buf size. This is not harmful, but will waste some space in file buffer. This patch make add_to_iovec() return 1 when it has flushed the file. Then the caller could check the return value to see whether it is necessary to adjust the buf_index any more. Signed-off-by: Wei Yang Reviewed-by: Dr. David Alan Gilbert Message-Id: <20190911132839.23336-3-richard.weiyang@gmail.com> Signed-off-by: Dr. David Alan Gilbert --- migration/qemu-file.c | 43 ++++++++++++++++++++++++++----------------- 1 file changed, 26 insertions(+), 17 deletions(-) diff --git a/migration/qemu-file.c b/migration/qemu-file.c index 66627088d4..26fb25ddc1 100644 --- a/migration/qemu-file.c +++ b/migration/qemu-file.c @@ -381,8 +381,16 @@ int qemu_fclose(QEMUFile *f) return ret; } -static void add_to_iovec(QEMUFile *f, const uint8_t *buf, size_t size, - bool may_free) +/* + * Add buf to iovec. Do flush if iovec is full. + * + * Return values: + * 1 iovec is full and flushed + * 0 iovec is not flushed + * + */ +static int add_to_iovec(QEMUFile *f, const uint8_t *buf, size_t size, + bool may_free) { /* check for adjacent buffer and coalesce them */ if (f->iovcnt > 0 && buf == f->iov[f->iovcnt - 1].iov_base + @@ -400,6 +408,19 @@ static void add_to_iovec(QEMUFile *f, const uint8_t *buf, size_t size, if (f->iovcnt >= MAX_IOV_SIZE) { qemu_fflush(f); + return 1; + } + + return 0; +} + +static void add_buf_to_iovec(QEMUFile *f, size_t len) +{ + if (!add_to_iovec(f, f->buf + f->buf_index, len, false)) { + f->buf_index += len; + if (f->buf_index == IO_BUF_SIZE) { + qemu_fflush(f); + } } } @@ -429,11 +450,7 @@ void qemu_put_buffer(QEMUFile *f, const uint8_t *buf, size_t size) } memcpy(f->buf + f->buf_index, buf, l); f->bytes_xfer += l; - add_to_iovec(f, f->buf + f->buf_index, l, false); - f->buf_index += l; - if (f->buf_index == IO_BUF_SIZE) { - qemu_fflush(f); - } + add_buf_to_iovec(f, l); if (qemu_file_get_error(f)) { break; } @@ -450,11 +467,7 @@ void qemu_put_byte(QEMUFile *f, int v) f->buf[f->buf_index] = v; f->bytes_xfer++; - add_to_iovec(f, f->buf + f->buf_index, 1, false); - f->buf_index++; - if (f->buf_index == IO_BUF_SIZE) { - qemu_fflush(f); - } + add_buf_to_iovec(f, 1); } void qemu_file_skip(QEMUFile *f, int size) @@ -760,11 +773,7 @@ ssize_t qemu_put_compression_data(QEMUFile *f, z_stream *stream, } qemu_put_be32(f, blen); - add_to_iovec(f, f->buf + f->buf_index, blen, false); - f->buf_index += blen; - if (f->buf_index == IO_BUF_SIZE) { - qemu_fflush(f); - } + add_buf_to_iovec(f, blen); return blen + sizeof(int32_t); }